Ultrasonography of the Metacarpal/Tarsal-Phalangeal Joints in Healthy Racehorses: Normal Appearance, Breed-Related and Age-Related Features.
Authors: Nocera Irene, Puccinelli Caterina, Sgorbini Micaela, Bagnoli Emma, Citi Simonetta
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Ultrasonography of Metacarpal/Tarsal-Phalangeal Joints in Healthy Racehorses Whilst ultrasound reference values exist for several major equine joints, the fetlock—arguably the most heavily loaded joint in racehorses—has lacked standardised normal parameters against which to compare pathological findings. This 2022 study examined 71 fetlocks across 28 healthy racehorses (15 thoroughbreds and 13 standardbreds) using high-frequency linear transducers to establish baseline articular cartilage thickness, appearance, and subchondral bone characteristics, stratified by age (< 5 years versus ≥ 5 years) and breed. Standardbreds demonstrated statistically significant age-related increases in cartilage thickness compared to younger animals, particularly in transverse measurements, whilst thoroughbreds showed no meaningful thickness variation across age groups; notably, no significant differences emerged between the two breeds overall, and all young standardbreds presented with structurally normal cartilage and bone surfaces. These breed-specific and age-related observations are clinically important because cartilage morphology adapts continuously in response to maturation, cumulative training load, and individual athletic demands—meaning practitioners now have evidence-based reference ranges to distinguish normal physiological variation from early degenerative change when assessing fetlock health via ultrasound. Establishing these breed and age-specific baselines allows farriers, veterinarians, and rehabilitation specialists to interpret fetlock ultrasounds more confidently and potentially identify subclinical pathology before it manifests clinically.
Read the full abstract on PubMed
Practical Takeaways
- •Establish breed- and age-specific reference values for fetlock ultrasound interpretation in racehorses, as cartilage thickness varies between standardbreds and thoroughbreds across age groups
- •Use caution when interpreting fetlock cartilage thickness in younger standardbreds (<5 years), as thinner cartilage is normal for this population and should not be mistaken for pathology
- •Develop breed-specific ultrasound protocols and baseline measurements for your practice to accurately distinguish normal developmental changes from joint disease
Key Findings
- •Cartilage thickness in standardbreds was significantly lower in horses <5 years old compared to ≥5 years old, except for lateral thickness in longitudinal view
- •No age-related differences in cartilage thickness were detected in thoroughbreds
- •All young standardbreds (group A) demonstrated normal cartilage and subchondral bone appearance on ultrasonography
- •No significant differences in ultrasound features were found between thoroughbred and standardbred breeds